The focus of this new project is a model system for exploring the specific targeting of tumor cells for immune destruction in the setting of bone marrow transplantation. The model system is EBV(+) Hodgkin's disease and is chosen because the relevant antigens are particularly well-defined, the role of bone marrow transplantation for the treatment of Hodgkin's disease accepted, and the existence of a strong cytotoxic T cell response to an EBV latency antigen expressed in Hodgkin's disease well established. In order to lay the groundwork for clinical trails, we will better define the cellular immune response to EBV latency antigens in patients with Epstein-Barr virus (EBV) associated Hodgkin's disease and HLA-matched potential donors. T cells stimulated by autologous EBV lymphoblastoid cell lines will be cloned at limiting dilution. The antigen specificity of the T cell clones will be determined in terms of specific EBV latency genes. This will be accomplished using a panel of 10 EBV-vaccinia recombinant to infect fibroblasts which will serve as targets. The specificities of the patient's cytotoxic T cells will be assessed on autologous fibroblasts. The specificity of potential donor's cytotoxic T cells will be assessed on autologous fibroblasts. T cells lines and clones directed against EBV from potential donors will be grown up in bulk culture. The lytic activity and specificity of the bulk cultures will be reassessed using the panel of EBV-vaccinia recombinants and the patient's fibroblasts. The potential of the bulk cultures to cause grafts vs host disease will be assessed by incubation of lymphocytes with skin explant from the patient. A SCID mouse model of human EBV-lymphoproliferative disease will be used to further asses safety and efficacy of the bulk cultures. Following these studies, a phase I trial of adoptive immunotherapy with either expanded polyclonal T cell lines or T cell clones will be undertaken. Patients with therapy resistant EBV-associated Hodgkin's disease will be studied. Patients undergoing either autologous or allogeneic marrow donor. In a parallel approach, we will explore the role vaccination of bone marrow donors and recipients to boosts the cytotoxic T cell response to relevant EBV proteins. To this end we will be construct a recombinant vaccinia expressing relevant EBV proteins with a "fail-safe" suicide gene to ensure safety when used in immunocompromised patients at the time of transplant. The safety of the vaccine will be evaluated in mice with well characterized immunodeficiencies (SCID, nude). If the "fail safe" mechanism passes muster in the mice phase I trials in patients with refractory EBV (+) Hodgkin's disease will begin. If not, then alternative vaccines will be evaluated.